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# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
# implied.
# See the License for the specific language governing permissions and
# limitations under the License.
from __future__ import absolute_import, division, print_function
from cryptography import utils
from cryptography.exceptions import UnsupportedAlgorithm, _Reasons
from cryptography.hazmat.backends.interfaces import (
CMACBackend, CipherBackend, DSABackend, HMACBackend, HashBackend,
PBKDF2HMACBackend, RSABackend
)
@utils.register_interface(CMACBackend)
@utils.register_interface(CipherBackend)
@utils.register_interface(HashBackend)
@utils.register_interface(HMACBackend)
@utils.register_interface(PBKDF2HMACBackend)
@utils.register_interface(RSABackend)
@utils.register_interface(DSABackend)
class MultiBackend(object):
name = "multibackend"
def __init__(self, backends):
self._backends = backends
def _filtered_backends(self, interface):
for b in self._backends:
if isinstance(b, interface):
yield b
def cipher_supported(self, algorithm, mode):
return any(
b.cipher_supported(algorithm, mode)
for b in self._filtered_backends(CipherBackend)
)
def create_symmetric_encryption_ctx(self, algorithm, mode):
for b in self._filtered_backends(CipherBackend):
try:
return b.create_symmetric_encryption_ctx(algorithm, mode)
except UnsupportedAlgorithm:
pass
raise UnsupportedAlgorithm(
"cipher {0} in {1} mode is not supported by this backend".format(
algorithm.name, mode.name if mode else mode),
_Reasons.UNSUPPORTED_CIPHER
)
def create_symmetric_decryption_ctx(self, algorithm, mode):
for b in self._filtered_backends(CipherBackend):
try:
return b.create_symmetric_decryption_ctx(algorithm, mode)
except UnsupportedAlgorithm:
pass
raise UnsupportedAlgorithm(
"cipher {0} in {1} mode is not supported by this backend".format(
algorithm.name, mode.name if mode else mode),
_Reasons.UNSUPPORTED_CIPHER
)
def hash_supported(self, algorithm):
return any(
b.hash_supported(algorithm)
for b in self._filtered_backends(HashBackend)
)
def create_hash_ctx(self, algorithm):
for b in self._filtered_backends(HashBackend):
try:
return b.create_hash_ctx(algorithm)
except UnsupportedAlgorithm:
pass
raise UnsupportedAlgorithm(
"{0} is not a supported hash on this backend".format(
algorithm.name),
_Reasons.UNSUPPORTED_HASH
)
def hmac_supported(self, algorithm):
return any(
b.hmac_supported(algorithm)
for b in self._filtered_backends(HMACBackend)
)
def create_hmac_ctx(self, key, algorithm):
for b in self._filtered_backends(HMACBackend):
try:
return b.create_hmac_ctx(key, algorithm)
except UnsupportedAlgorithm:
pass
raise UnsupportedAlgorithm(
"{0} is not a supported hash on this backend".format(
algorithm.name),
_Reasons.UNSUPPORTED_HASH
)
def pbkdf2_hmac_supported(self, algorithm):
return any(
b.pbkdf2_hmac_supported(algorithm)
for b in self._filtered_backends(PBKDF2HMACBackend)
)
def derive_pbkdf2_hmac(self, algorithm, length, salt, iterations,
key_material):
for b in self._filtered_backends(PBKDF2HMACBackend):
try:
return b.derive_pbkdf2_hmac(
algorithm, length, salt, iterations, key_material
)
except UnsupportedAlgorithm:
pass
raise UnsupportedAlgorithm(
"{0} is not a supported hash on this backend".format(
algorithm.name),
_Reasons.UNSUPPORTED_HASH
)
def generate_rsa_private_key(self, public_exponent, key_size):
for b in self._filtered_backends(RSABackend):
return b.generate_rsa_private_key(public_exponent, key_size)
raise UnsupportedAlgorithm("RSA is not supported by the backend",
_Reasons.UNSUPPORTED_PUBLIC_KEY_ALGORITHM)
def create_rsa_signature_ctx(self, private_key, padding, algorithm):
for b in self._filtered_backends(RSABackend):
return b.create_rsa_signature_ctx(private_key, padding, algorithm)
raise UnsupportedAlgorithm("RSA is not supported by the backend",
_Reasons.UNSUPPORTED_PUBLIC_KEY_ALGORITHM)
def create_rsa_verification_ctx(self, public_key, signature, padding,
algorithm):
for b in self._filtered_backends(RSABackend):
return b.create_rsa_verification_ctx(public_key, signature,
padding, algorithm)
raise UnsupportedAlgorithm("RSA is not supported by the backend",
_Reasons.UNSUPPORTED_PUBLIC_KEY_ALGORITHM)
def mgf1_hash_supported(self, algorithm):
for b in self._filtered_backends(RSABackend):
return b.mgf1_hash_supported(algorithm)
raise UnsupportedAlgorithm("RSA is not supported by the backend",
_Reasons.UNSUPPORTED_PUBLIC_KEY_ALGORITHM)
def decrypt_rsa(self, private_key, ciphertext, padding):
for b in self._filtered_backends(RSABackend):
return b.decrypt_rsa(private_key, ciphertext, padding)
raise UnsupportedAlgorithm("RSA is not supported by the backend",
_Reasons.UNSUPPORTED_PUBLIC_KEY_ALGORITHM)
def encrypt_rsa(self, public_key, plaintext, padding):
for b in self._filtered_backends(RSABackend):
return b.encrypt_rsa(public_key, plaintext, padding)
raise UnsupportedAlgorithm("RSA is not supported by the backend",
_Reasons.UNSUPPORTED_PUBLIC_KEY_ALGORITHM)
def generate_dsa_parameters(self, key_size):
for b in self._filtered_backends(DSABackend):
return b.generate_dsa_parameters(key_size)
raise UnsupportedAlgorithm("DSA is not supported by the backend",
_Reasons.UNSUPPORTED_PUBLIC_KEY_ALGORITHM)
def generate_dsa_private_key(self, parameters):
for b in self._filtered_backends(DSABackend):
return b.generate_dsa_private_key(parameters)
raise UnsupportedAlgorithm("DSA is not supported by the backend",
_Reasons.UNSUPPORTED_PUBLIC_KEY_ALGORITHM)
def create_dsa_verification_ctx(self, public_key, signature, algorithm):
for b in self._filtered_backends(DSABackend):
return b.create_dsa_verification_ctx(public_key, signature,
algorithm)
raise UnsupportedAlgorithm("DSA is not supported by the backend",
_Reasons.UNSUPPORTED_PUBLIC_KEY_ALGORITHM)
def create_dsa_signature_ctx(self, private_key, algorithm):
for b in self._filtered_backends(DSABackend):
return b.create_dsa_signature_ctx(private_key, algorithm)
raise UnsupportedAlgorithm("DSA is not supported by the backend",
_Reasons.UNSUPPORTED_PUBLIC_KEY_ALGORITHM)
def dsa_hash_supported(self, algorithm):
for b in self._filtered_backends(DSABackend):
return b.dsa_hash_supported(algorithm)
raise UnsupportedAlgorithm("DSA is not supported by the backend",
_Reasons.UNSUPPORTED_PUBLIC_KEY_ALGORITHM)
def dsa_parameters_supported(self, p, q, g):
for b in self._filtered_backends(DSABackend):
return b.dsa_parameters_supported(p, q, g)
raise UnsupportedAlgorithm("DSA is not supported by the backend",
_Reasons.UNSUPPORTED_PUBLIC_KEY_ALGORITHM)
def cmac_algorithm_supported(self, algorithm):
return any(
b.cmac_algorithm_supported(algorithm)
for b in self._filtered_backends(CMACBackend)
)
def create_cmac_ctx(self, algorithm):
for b in self._filtered_backends(CMACBackend):
try:
return b.create_cmac_ctx(algorithm)
except UnsupportedAlgorithm:
pass
raise UnsupportedAlgorithm("This backend does not support CMAC",
_Reasons.UNSUPPORTED_CIPHER)
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